Existing X-ray imaging systems detect internal structures of an object in a non-destructive way based on attenuation properties of materials to X-rays, in order for material recognition or security check. For example, a transmission type luggage inspection apparatus that performs security check on luggage uses X-ray to perform transmission imaging of an object under check, to obtain an image which is attenuated in the transmission direction. Then, it is determined whether the object under check contains a dangerous article or not based on shapes or transmission values of articles included in the attenuation image which is represented in gray levels. Further, a CT-type luggage inspection apparatus performs CT scan on an object under check to obtain a section image of the object under check at a certain position, so as to determine internal structures of the object under check more precisely, for more precise material recognition and security check. However, those techniques have disadvantages such as false alarm or incorrect recognition. There is still a need for techniques for more precise and rapid check.